be aware that evaling something read from an external file or STDIN is highly insecure. In an untrusted environment, you should check the input (and use taint checking): 
$foo = <STDIN>;
if ($foo =~ /^(\d*)$/) {
  $foo = eval $1;
  print "foo: $foo\n"
}
else {
  die "bad input"
}

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In reply to Re^2: <STDIN> always in string mode? by salva
in thread <STDIN> always in string mode? by kiz

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